Rotary transfer valve



1952 A. B. KENNEDY ROTARY TRANSFER VALVE 3 Sheets-Sheet 1 Filed Dec. 5, 1946 .57- j mun aim; ATTORI EY 44 INVENTOR a, gigqusfizfivz e y 1952 A. B. KENNEDY ROTARY TRANSFER VALVE 3 Sheets-Sheet 2 J6 2e! 42 4% Filed Dec. 5, 1946 2 m m K 1. m w a A 4 F .Y 1% m U W J Feb. 12, 1952 A. B. KENNEDY 2,585,472

ROTARY TRANSFER VALVE Filed Dec. 5, 1946 3 Sheets-Sheet 3 Q N Q I 7/ fla 1% Iilwentor Patented Feb. 12, 1952 2,585,472 ROTARY TRANSFER VALVE Angus B. Kennedy,

Cincinnati, Ohio;

Vera

Alward. Kennedy, administratrix of said Angus B. Kennedy, deceased, assignor to Vera, Alward Kennedy, Cincinnati, Ohio Application December- 5, 1946, Serial No. 714,183

This invention relates to improvements in a rotary valve designed to transfer separate masses of flcwable pulverulent material from a region at one pressure to a second region at another pressure. More particularly it relates to improved means for providing a more perfect air seal between parts of the rotor and the rotor housing of the valve and to an improved method and means for displacing from the valve chambers air acquired during a period of discharging pulverulent material into a region of higher pressure.

In processes involving the solvent extraction of oils from pulverized vegetable matter or the milling of cereal grains, continuous vacuum driers are used for driving on the adsorbed solvent or the contained moisture, as the case may be. The material to be dried is admitted from a region at ordinary pressures into one end of aheated chamber, which is under a pressure less than atmos pheric, and after being dried, is removed from the other end of the chamber into a region usually at ordinary atmospheric pressure. The drying process is most economically carried out in a con tinuous manner and in order not to raise the air pressure unduly within the vacuum chamber it is desirable to effect the entrance of the material into the chamber and the removal after treatment with the admission of as little air as possible.

This problem has been met heretofore by the use of a rotary transfer valve having a number of blades dividing the rotor into a plurality of distinct compartments. Since difierent chambers are exposed to the air and to the vacuum cham= ber at any one time there is no continuous passage which would enable the outside atmosphere to leak into the vacuum chamber.

It will be readily seen from their general construction, however, that these rotary valves do not normally provide a perfect means of preventing ingress of outside air to the vacuum chamber during the transfer process One objection to the valves as formerly constructed is that the rotor blades did not make air tight contact with the valve housing and the contact became in creasingly poor as the valve became worn in operation. This not only resulted in undesirable quantities of air leaking from the atmosphere into the vacuum chamber but allowed outside dust to be swept in as well.

Another inherent fault has been that every time a compartment comes into register with the opening leading to the region or higher pressure, i. 'e.', the atmosphere, air rushes in piling the 9 Claims. (Cl. 302-49) compartment, then is carried around as the rotor continues to turn and is discharged into the vacuum chamber. Each puff of air entering the vac uum chamber not only causes added strain on the pumps striving to maintain the reduced pressure therein but raises a cloud of dust particles, as well, if the pulverulent material has a larg proportion of fines. These 'fines may be sucked out' of the chamber into the vacuum pump instead of being normally discharged through the rotary valve and will quickly clog any filter placed in the vacuum line to intercept them.

The primary object of my present invention is to provide an improved rotary valve of the type under consideration which will be free from the above noted and other similar disadvantages in herent in prior art valves of this type. More particularly, it is an object of the present invention to provide an improved sealing means adapted to be placed on the transverse ends of the roto blades of a rotary transfer valve.

Another object of the invention is to provide an improved holder for said sealing means.

Another object of the invention is to provide an improved air sealing means positioned be tween the end plates forming part of the rotor and attached to the lateral ends of the radial blades of a rotary transfer valve, and the interior cylindrical wall of the valve housing.

Another object of the invention is to provide an improved method of expelling the air by displacement from a compartment of a rotary trans fer valve placed at the discharge side of a vacuum drying chamber which air the said compartment has acquired while discharging a load of material to a region under higher pressure.

Still another object of the invention is to provide means for admitting steam into successive compartments of a rotary transfer valve for the purpose of driving out contained air.

Other objects and advantages will be apparent and the invention will be better understood from the following description and reference to the accompanying drawings of which v Fig. lis a side elevation view of one form of rotary valve structure constructed in accordance with my present invention,

Fig. '2 is a sectional'view, partly broken away, taken along the line IIII of Fig. 1,

Fig. 3a is a fragmentary sectional view of the discharge end of a preferred form of rotary valve housing in accordance with my presentinvention,

Fig. 3b is an enlarged "elevation, partly in section, of the steam discharging nozzle of 3d,

Fig. 4 is a sectional view of a double olosure ring which may be used to form an improved air seal between the end plates of the rotor and the valve housing,

Fig. 5 is a longitudinal section view of the end of a rotor blade and a portion of the associated end plates together with a part of the valve housing,

Fig. 6 is a side elevation, partly in section of a further form of rotary valve according to my present invention, and incorporating difierent means for admitting steam to the valve compartments from that shown in Fig. 3a,

Fig. 7 is an end view of the embodiment illustrated in Fig. 6, and

Fig. 8 is an end view of one of the rotor end plates used in the embodiment illustrated in Figs. 6 and '7.

Referring more particularly to Figs. 1, 2, and 5, the improved valve structure of the present invention there shown comprises a rotor 2 fixed to a shaft 4 and enclosed in a cylindrical housing 6 so as to rotate therein about a horizontal axis; The rotor 2 has a number. of blades 8 to which are bolted end plates 10 and I2 which, together with the blades 8, provide the rotor with a series of compartments [4. When the valve is in operation, the compartments move successively into register with an inlet passage IS in the top of the housing 6 to receive a charge of material and then move into register with a discharge passage l8 in the bottom of the housing to discharge the material from the compartments.

Whenthe valve is located at the discharge end of a vacuum drying chamber, for example, the inlet passage It leads into a hopper 2B which in turn, communicates with the interior of the chamber, not shown. The outlet passage l8 communicates with a region of h gher pressure. such as the outside atmosphere. One of the principal functions of the blades 8 is to make sliding contact with the cylindrical inner wall of the housing 5 while maintaining a seal which is as air tight as is practically possible. This is to prevent the passage of atmospheric air through the valve from the discharge passage l8 to the inlet l6.

Improved means for maintaining the air-tight seal are a part of the present invention. As shown in Fig. 2, seal holders 22 are fitted over the transverse ends of rotor blades 8, these ends of the blades being preferably fitted into recesses 24 cut in the holders as illustrated. The outer side portions of the blades 8 which are received in the recesses 24 and the interior side walls of the recesses 24, themselves, are made to fit each other exactly by grinding and polishing in order to help minimize air leaks at these points. The ends of the seal holders 22 which are intended to face the interior walls of the housing 6 are also recessed and into the recesses thereof are fitted means for providin a renewable wearing surface. These means may be fiber strips 26 which may be impregnated with graphite to reduce friction.

As shown in Fig. 5, the wearing surfaces of the strips 26 are resiliently pressed against the interior housing wall in a direction radially outwardly from the center of rotation of the rotor by means of springs 28 inserted in recesses 30 formed in the ends of the rotor blades 8. The springs exert their force against the lower contacting surfaces of seal holders 22 which, in turn, transmit the force to the strips 26. Through this arrangement. there is maintained a constant, tight fit between the sealing means and the housing wall even though the fiber strips may become constantly thinner through frictional wear.

A channel 32 is provided between the ends of each of the rotor blades 8 and the bottoms of the recesses 24 in the seal holders 22. Alemite or other suitable fittings 32 in the end plates ill and i2 supply lubricant to the channels 32 for the purpose of lubricating and sealing the bearing surfaces between the holders 22 and the rotor blades 8. These fittings also lubricate and seal the space between end plates in and I2 and seal holders 22.

Alemite or like fittings 36 supply lubricant to oil grooves 38 at the points where the end plates l0 and I2 have a running fit against the inside bore of valve housing 6. Other fittings 40 supply lubricant to the double closure sealing rings 42 which are included to provide additional improved means of forming an airtight seal between the end plates and the valve housing. The sealing rings 42 are made of flexible fiber material. They are attached to the stepped portion 44 of the valve housing by means of a channeled metal holder 46. A resilient cushion 41, made of felt, for example, may be mounted between the closure ring 42 and the adjacent wall portion of the housing 6, as shown in Fig. 4, for the purpose of sealing in the lubricant and keeping out dust.

Other forms of sealing means may be used in place of the fiber strips 26 held in the seal holders 22. The seal holders, themselves, may be made of brass or other soft metal and their outer contactsurfaces may be machined and ground so as to provide a tight fit against the interior surface of the valve housing. A

It is also possible, although less preferable, to use other sealing means in place of the double closure rings 42. Recessed metal rings and flexible ring packing can be substituted if desired.

Although illustrated in connection with a transfer valve located at the discharge end of a vacuum drying chamber, the improved air sealing means are obviously not limited to valves used in this manner. The sealing means may be used in any rotary transfer valve located at a point be tween regions of two different pressures in a vac uum drying system or any other system using varied pressures in different parts.

The present invention includes certain other improvements relating to rotary valves of the character described which are more especially designed to discharge material from a vacuum drying chamber. These improvements have to do with methods and means of preventing air from being carried into the vacuum drying chamber.-

As shown in Fig. 2, during the normal opera tion of a rotary valve connected to the discharge end of a vacuum dryer, each compartment M, as it discharges its contained pulverulent material into the discharge passage i3, becomes filled with air. This air is carried around with the blades and, if nothing is done to remove it, enters the vacuum chamber through the passage it. Most of this air can be driven out of the compartment by the improved method, one embodiment of which is illustrated in Fig. 3a. This comprises one or more steam jets 48 having suitable control Valves 50 and 52 and a nozzle 54 placed just within the entrance to the discharge passage I8. As one of the revolving compartments l4 empties itself of material into the passage I8, the jet 48 is made to inject a quantity of steam into the said compartment-expanding the air therein and driving-most of it out through the discharge passage iii. .fllthough steam is perhaps the cheapest and 8 "most convenient substance to use in driving out the air, other easily condns'able gaseous med-1a; heated lir'unhatedmay be used. For example, ethylene g1 1 or carbon tetrachloride or other similar c'rganc materials may be used in the vapor 'statesin'ce they can be made to condense t6 relatively small liquid volumes with relative ease by quickly lowering their temperature. The action of the gaseous material is largely in the nature or displacement of the air in the com= partnient. The purged compartment continues to revolve and eventually reaches a position out or register with the discharge passage. The steam, which is preferably dry and may be superheated, or other easily condensable gaseous medium which may be used, will not conde'ns'e appreciably on the rotor blades since the blades are-heated by the material being discharged from the hot drying chamber. The relatively small amount of 'air remaining in the compartment and the steam enter the vacuum chamber when the compartment again comes into register withinlet passage IE but the quantity of each is so small that the vacuum system can easily handle it.

Another embodiment of this feature is illustrated in the improved form of apparatus of Figs. 6; 7, and 8 wherein the injection of steam into the compartments is accomplished in a more positive and automatic manner. In this form of my invention, one of the end plates 56 is provided with an additional hub portion 58 having a number of ports 50 drilled therethrough. Each port connects with a separate compartment l4 of the rotor.

There is also provided a stationary port ring 62 which rides freely on the rotor shaft 4. This ring is held firmly against theface of hub 53 by pressure of a spring 64 backed by a bushing 66. The port ring 62 is provided with a single port 68 located on the same radius with respect to the axis "of the rotor 2 as the ports 66. Steam is supplied to the port 68 by means of a steam line 16 having a flexible section 12. A yoke M attached to an end bearing 16 with capscrews 18 also engages steam line Ill by means of a forked portion 86 and since the end of the steam line is rigidly connected to the port ring 62, the ring is thus prevented from turning on the rotor shaft '4. Slotted screw holes 82 provided for the capscrews 18 which attach the yoke 14 to the bearing 16 permit some adjustment so that port ring 62 can be turned slightly on its axis.

By the above arrangement, steam is admitted successively to each compartment [4 through its entrance port 60 as that port comes into alignment with the port 68 in the port ring. The port 68 is positioned so that steam is admitted automatically to each valve compartment in turn just after its contained material has been discharged and before its following rotor blade has cut the compartment off from the discharge pasage IS. The valve turns slowly, at but a few revolutions per minute, so that by the time the compartment is cut oif from the passage l8. air has been expelled from it and the compartment has been filled with steam. The slotted screwholes 82 permit the timing of the steam entrance to be suitably adjusted for different speeds or different loads of pulverulent material.

From the foregoing description, it will be apparent that there has been provided an improved rotary transfer valve especially adapted to be used with vacuum drving systems and which operates more efiiciently than similar prior art valves and which can be run with greater economy. Moreover, the improvements incorporated in my inventionare useful in connection with transfer valves used in general to conduct :pulverulent or other material-between regions at difierent pressures-and are susceptible of hum"- erous modifications other than the embodiments illustrated. For example, in the handling of some types of materials, the rotary valve placed at the inlet side of a vacuum drying chamber may also be fitted with steam entrance ports similar to those described in connection with a rotary valve placed at the discharge side of the drying cham her. In this case, the steam is preferably injected into each valve compartment just beforeit comes into register with the inlet passage and, conse-" quently, before it has received a charge of ma-' terial to be carried around to the vacuum chamrbera In thi embodiment, the function of the steam is not to drive out air from the compartment but rather to neutralize the suction efiect caused by the difference in pressure between the evacuated'valve compartment and the normal atmospheric conditions at the inlet passage. The steam also mixes with the material enteringthe valve compartment and tends to prevent air from being trappfid between the particles and then being carried around to the vacuum chamber. In the case of either the inlet or the discharge valves, however, itwill be seen that the function of the steam in the compartments is essentially the same. In each instance, it acts to prevent an undue amount of air from being carried from the high pressure side to the low pressure side of the valve.

1. A rotary transfer valve comprising a rotor having a plurality of compartments means providing an inlet passage for communicating with a region under low pressure means providing'an outlet passage for communicating with a region under high pressure, and means connected to said outlet passage providing means for injecting steam successively into each of said compartments through said outlet passage. 2 A rotary valve mechanism having a rotor divided into a plurality of compartments, said rotor being adapted to receive and to discharge pulverulent material at difierent points along the outer circumference of its path of rotation, and means independent of said rotor for, injecting steam into each of said rotor compartments through said point of discharge while each said compartment is passing said point of discharge.

3. A rotary valve for transferring material from one station to another station comprising a housing having a cylindrical inner wall, a bushing external to said housing, a shaft rotatably carried in said bushing, a rotor having a plurality of radial blades and a pair of endplates secured thereto, said rotor being connected to said shaft and being mounted within said housing, closure rings of resilient material mounted on said cylindrical inner wall and making airtight contact with the circumferential edges of each of said endplates, and retaining members for said closure rings interposed between said cylindrical inner wall and said closure rings, said closure rings and retaining members being separate from said bushing and said shaft.

4. A rotary valve for transferring material from one station to another station comprising a housing having an inner wall, a bushing external to said housing, a shaft rotatably carried in said bushing, a rotor having a plurality of radial blades and a pair of endplates secured thereto, said rotor being connected to said shaft and being mounted within said housing, closure rings of resilient material mounted on said inner wall and making airtight contact with a surface of each of said endplates, and retaining members for said closure rings interposed between said inner wall and said closure rings, said closure rings and retaining members being separate from said bushing and said shaft.

5. A valve mechanism for transferring material from one station to another station which comprises a housing having an inlet for communication with said one station and an outlet for communication with said other station, means within said housing providing a plurality of material transferring compartments, said means being movably mounted for movement of said compartments alternately to and from said inlet and said outlet and having fluid tight engagement with said housing, and means connected to said housing at said outlet for introducing into each one of said compartments through said outlet while said compartments are successively at said outlet an easily condensable, gaseous medium for displacing the air therein as said first means moves to advance each said compartment from said outlet to said inlet.

6. A valve mechanism according to claim in which said housing is cylindrical in shape and in which said first named means provides a plurality of circumferentially arranged compartments rotatably mounted on the axis of said housing.

7. A valve mechanism according to claim 5 in which said housing is cylindrical in shape and in which said first named means includes (1) a plu rality of blades which extend radially outwardly from a common center and (2) a pair of endplates secured thereto.

8. A valve mechanism for transferring material from a station at low pressure to a station at high pressure which comprises a housing having an inlet for communication with said station at low pressure and an outlet for communication with said station at high pressure, means within said housing providing a plurality of material transferring compartments, said means being movably mounted for movement of said compartments alternately to and from said inlet and said outlet, air sealing means having a renewable wearing surface mounted between said first mentioned means and said housing, and means connected to said housing at said outlet for introducing into each one of said compartments successively through said outlet an easily condensable gaseous medium for displacing the air therein as said first mentioned means moves to advance each of said compartments from said outlet to said inlet.

9. A valve mechanism for transferring material from a station at low pressure to a station at high pressure which comprises a housing having an inlet for communication with said station at low pressure and an outlet for communication with said station at high pressure, a rotor mounted within said housing, said rotor having a plurality of radial blades provided with recesses at the outer ends thereof and a pair of endplates secured thereto and cooperating with said blades to provide a plurality of material transferring compartments, separate and removable sealing means positioned on said outer ends of each of said blades for making a fluid tight seal between said blades and the inner wall of said housing, means within said recesses for exerting pressure on each of said sealing means in a direction radially outward from the axis of rotation of said rotor, closure 'rings of resilient material mounted on the inner wall of said housing and making airtight contact with a surface of each of said endplates, and means connected to said housing at said outlet for injecting steam into each of said compartments through said outlet while it is in registry with said outlet.

ANGUS B. KENNEDY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 216,369 Atwell June 10, 1879 476,608 Calkins June 7, 1892 941,024 Mantius Nov. 23, 1909 1,646,577 Chapman Oct. 25, 1927 1,978,656 Thompson Oct. 30, 1934 2,026,732 Farley Jan. 7, 1936 2,314,031 Colburn Mar. 16, 1943 

